FR2617582A1 - Oven for drying and baking refractory products - Google Patents

Abstract

Oven for drying and baking refractory products characterised in that it comprises: a fixed rear part 1, a carriage 2 provided to be set into the fixed rear part 1 and being formed of a horizontal base 3 which can move for depositing prefabricated refractory elements 21 and of a vertical part 4 allowing the possible passage of some portions of the prefabricated elements and, finally, a part forming a lid 5 which is to cover the fixed rear part 1 and the carriage 2, the part forming the lid 5 having means 25 for possibly suspending other prefabricated elements, heating devices for the inside of the oven also being provided as well as members 18 for detecting the internal temperature of the oven.

Description

 The present invention relates to an oven for the gradual drying and baking at the desired temperature of refractory products, and in particular prefabricated elements produced from metal reinforcements or frameworks covered, at least in part, with refractory materials, and which are used in particular in the steel industry to be brought into contact with liquid steel.

It also extends to such treatment of prefabricated elements made entirely of refractory materials without metal frames or frames.

 The oven according to the invention makes it possible to obtain an appropriate cohesion of the molecules of the refractory aggregates, without deterioration of the binders and components, until sintering or until the necessary transformation of these aggregates for sufficient resistance to strong thermophysical shocks to contact with liquid steels, thereby making it possible to very significantly reduce the overall cost of such prefabricated elements.

 It should indeed be noted that it has not been possible until now to correctly treat prefabricated elements of the above type, and in particular prefabricated elements comprising metallic reinforcements covered only in part with refractory materials , such as "cattails" used to blow gas into a bath of molten steel and the end of which forms a gas passage pipe is not covered with refractory materials. In fact, so as not to expose the overcoated metal reinforcements to too high a heat, the refractory materials of such prefabricated elements were then not sufficiently cooked or even sufficiently dried and caused the dangerous formation of bubbles in contact with the molten steel. In addition, due to the lack of cohesion of the refractory aggregates, the lifetime of such elements was relatively short.

 The invention solves the above problem in a particularly suitable manner by creating an oven for drying and cooking refractory products, having a modular cover and a movable floor with multiple functions having in particular the possibility of leaving outside the furnace the portions of the metal frames or frameworks not covered with refractory materials of the prefabricated elements subjected to drying and to firing, and intended in particular for the needs of industry, steel and steelworks.

 According to the invention, the oven comprises a fixed rear part, a carriage which fits into the fixed rear part and being formed by a movable horizontal hearth intended for the installation of prefabricated elements of the above type and of a vertical part provided for the possible passage of portions of the frameworks of prefabricated elements which are not covered with refractory materials, and finally a part forming a cover which must cover the fixed rear part and the carriage, said part forming a cover having means for the possible suspension of others. prefabricated elements; furnace interior heating devices are also provided as well as internal temperature detection members of the furnace.

 In accordance with another feature of the invention, the vertical part forming part of the floor, and delimiting with this sole the carriage, has openings for the passage of portions of the frameworks of the prefabricated elements, these prefabricated elements being supported, of a on the one hand, by the sole for the portions of the prefabricated elements covered with refractory materials and, on the other hand, by the reinforcement of the vertical part of the carriage for the portions of the prefabricated elements not covered with refractory materials and which thus exit, by said openings, outside the oven so as not to be subjected to the high temperature which must prevail in the oven to ensure the appropriate treatment of the refractory materials of the prefabricated elements.

 Various other characteristics of the invention will also emerge from the detailed description below.

 An embodiment of the object of the invention is shown, by way of nonlimiting example, in the accompanying drawing.

 Figure 1 is a top view of the cover portion of the oven, the roof of the cover being torn off and the figure showing prefabricated elements hanging from the cover.

 Figure 2 is a section of the oven taken along line II-II of Figure 1 and shows the oven closed.

Figure 3 is a section along the line
III-III of figure 1.

 FIGS. 4a and 4b are partial views of preferred embodiments of the openings delimited in the panel of the vertical parts of the oven closing carriage when the prefabricated elements to be treated comprise portions which must not be exposed to the internal heat of the oven.

 In the drawing, an oven is represented mainly consisting of a fixed rear part 1, a movable front part 2 constituting a carriage formed by a hearth 3 and a vertical panel 4, and finally by a cover 5.

 The fixed rear part 1 comprises an external metal frame 6 connected to attached elements 7 provided with ladders and access bridges to the cover 5. The portion of the fixed rear part 1 facing the interior of the oven, and which is thus mounted on the frame 6, is formed of a base 8 of refractory concrete having fittings 9, connected to the metal frame 6 and on the base 8 is placed a mounting of refractory bricks 9. Above the mounting of refractory bricks 9, and bearing on a metal angle 10 of the frame 6, the fixed rear part 1 ends in a wall 11 of refractory concrete, the fittings of which are also connected to the metal frame 6.

 The hearth 3 and the vertical panel 4 of the front part 2 of the oven delimits a carriage resting on a slab 12 using rollers 13. The front part 2 can thus be driven by means not shown in the drawing and can roll on the slab 12 to come to be embedded in the fixed rear part when the oven is closed. The front part 2 thus acts as the oven closing door and ceramic fibers 14 are provided to seal the joint between the fixed rear part 1 and the mobile part 2 in the closed position of the oven.

 Both the floor 3 and the vertical panel 4 of the movable part or carriage 2 comprise a metal frame 15a and, respectively, 15b covered with refractory concrete and are produced according to a usual technique similar to that used for the fixed rear part 1.

 Burners 16 are placed tangentially to the wall of the oven in an opposite oblique arrangement in order to produce a circular rotation, according to the arrows f, of the heat from the bottom to the top of the oven through a distribution plate 17, in order to set the temperatures requested by the user of the oven.

 The power of the burners 16, generally supplied with natural gas, is established according to the necessary temperature requests and can be adjusted as required. A thermometric probe shown diagrammatically at 18 constitutes a temperature control device and is connected in a known manner to a device with a temperature rise graph, placed outside the oven, for controlling the supply of the burners 16.

 As shown in the drawing and shown schematically in Figures 4a and 4b, the vertical panel 4 has openings 19 (i.e. portholes 19a in Figure 4a or grooves 19b with interposed spacer profiles covered with refractory materials to the FIG. 4b) for the passage outside the oven of metal portions 20 of prefabricated elements 21 partially covered with refractory materials, these metal portions 20 not being covered with refractory materials and thus projecting outside the oven so as not to be exposed to the high temperature of the oven heated by the burners 16.

 For example, such prefabricated elements 21 can be elements called "cattails" and comprise a tube constituting the metal portion 20 of FIG. 2 and serving to conduct an insufflation of gas and other components in a bath of molten steel.

 These cattails rest, on the one hand, on the floor by means of support blocks 22 of refractory materials mounted on logs of refractory steel 22a and, on the other hand, on the frame of the vertical panel of door 4 outside, the metal portions 20 of these cattails passing through the openings 19 of the panel.

 The support blocks 22 of the prefabricated elements or cattails 21 are placed on the sole 3 so as to delimit, in the carriage formed by the movable sole 3 and the vertical panel 4, intermediate empty spaces in which others can be placed prefabricated refractory parts to be dried or fired, such as casting seats, nozzles, slide valves, etc.

 It is also possible to remove the support blocks 22 and to deposit, directly on the floor 3 of the carriage 21, specific prefabricated elements such as runners for beak casting of electric ovens with prefabricated refractory blocks without metal framework.

In this case, the openings 9 are obviously closed for example by refractory portholes, or the vertical panel of the carriage 2 does not have such openings 9, since no part not covered with refractory materials must leave the oven, unlike the case previously considered.

 The modular cover 5 of the furnace is provided in the drawing for the suspension of prefabricated elements 23, such as desulphurization bells called "plungers" in terms of steel and steelworks. In the arrangement shown, the prefabricated elements 23 comprise a frame 24 connected to the frame 25 of the cover 5 and have at 26 an overlap of refractory materials. The closure plate 27 of the cover 5 has movable valves 28 provided with counterweights to allow, in the open position shown in phantom, a discharge of the various gases contained in the oven when their pressure becomes greater than a given value. It is also possible to provide a suction system with a fan to allow adjustment of the vacuum in the oven and in particular to obtain a constant vacuum.

 As seen above, just as the carriage 2 can be removed from the oven. for the installation of various prefabricated elements possibly different from those illustrated, the modular covers 5 may not have prefabricated suspended elements, for example in the case where prefabricated elements of greater height than those have been placed on the floor represented.

 A ring 29 allows the installation of various modular covers 5 on the rest of the structure of the oven in position. Guide members 30 provided, on the one hand, on the fixed part of the furnace and, on the other hand, on the cover cooperate in the closing of the furnace, and ceramic fiber seals 31 are provided for sealing.

 The invention is not limited to the embodiment shown and described in detail since various modifications can be made without departing from its scope. In particular, the dimensions of the furnace according to the invention are variable and are established in relation to the size of the prefabricated elements to be treated and according to the needs of the industry concerned. Similarly, and although an oven of rounded section has been shown in the drawing, the oven could just as easily have other shapes. The oven according to the invention also makes it possible to bake the refractory materials from the walls of the oven at the same time as the prefabricated refractory elements disposed inside the oven are treated. In addition, if for large series, the supports of the prefabricated elements placed on the floor can be made at least in part of highly refractory steel, for small series, it is possible to use prefabricated supports of refractory concrete.

Claims (10)

 1. Oven for drying and cooking refractory products, characterized in that it comprises  - a fixed rear part (1),  - a carriage (2) designed to come to be embedded in the fixed rear part (1) and being formed by a movable horizontal sole (3) for the installation of prefabricated refractory elements (21) and a vertical part ( 4) allowing the possible passage of certain portions of the prefabricated elements, and finally,  - a part forming a cover (5) which must cover the fixed rear part (1) and the carriage (2),  - the part forming a cover (5) having means (25) for the possible suspension of other prefabricated elements, heating devices 1163 of the interior of the oven also being provided, as well as members (18) for detecting the temperature internal oven.  2. Oven according to claim 1, characterized in that the vertical part (4) integral with the sole (3) and delimiting with this sole the carriage (2) has openings (19, 19a, 19b) for the passage of portions (20) of the prefabricated elements, these prefabricated elements (21) being supported, on the one hand, by the sole (3) for the portions of the prefabricated elements covered with refractory materials and, on the other hand, by the reinforcement of the vertical part (4) of the carriage (2) for the portions (20) of the prefabricated elements not covered with refractory materials and which thus exit, through said openings (19, 19a, 19b) outside the oven so as not to not be subjected to the high temperature which must prevail in the oven to ensure appropriate treatment of the refractory materials of the prefabricated elements.  3. Oven according to one of claims 1 or 2, characterized in that the exterior of the oven comprises a metal frame provided with a ladder and access bridges to the cover.  4. Oven according to one of claims 1 to 3, characterized in that the interior of the oven is covered with a coating of refractory materials.  5. Oven according to one of claims 1 to 4, characterized in that there are provided valves (28) for the evacuation of gases contained in the oven, when they reach a determined pressure.  6. Oven according to one of claims 1 to 5, characterized in that there is provided a suction system to allow adjustment of the vacuum inside the oven and in particular to obtain a constant vacuum.  7. Oven according to one of claims 1 to 6, characterized in that the burners (16) are arranged tangentially to the walls of the oven in an opposite oblique arrangement, so as to produce a circular rotation of the heat from the bottom to the high to set the temperatures requested by the user of the oven.  8. Oven according to one of claims 1 to 7, characterized in that there is provided a temperature probe arranged inside the oven and associated with a control device by temperature rise graph.  9. Oven according to one of claims 1 to 8, characterized in that the supports of the prefabricated elements on the hearth are made at least partly of refractory steel.  10. Oven according to one of claims 1 to 9, characterized in that the supports of the prefabricated elements on the hearth are made at least partly of refractory concrete.